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BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

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Old 01-20-2012, 02:34 AM
  #26
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale


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ORIGINAL: JariV

Johnny, please tell me how you know that? Are you ABSOLUTELY sure?

I think you are wrong. I don't see a problem with cooling when all the details are taken into account.

Yes, the STOCK engine rpm is around 8800 but this engine is not stock anymore. Ever heard about tuning? Tuning allows the engine to have more power over a wider band and with a tuned pipe you can extend the rpm band A LOT. Does the exhaust system look like it's a stock system for an aviation 2-stroke engine?

Secondly, the primary gears have been selected so that 10.000 rpms from the engine yield 60 mph speed for the car. That is only a starting point. And the torque coming from 100cc engine... well it's not lower that from a 23-30.5cc normal gas engines. Or 50 - 60cc engines.

Try to think outside the box and see the technical side. Not only catalogs or basic applications.
Sure the pipes will definitely give it more grunt and you did say that you ported the heads so itcould be a runner. 60mph from 10K rpm is gonna place a hel l of a load on the engine. But im sticking with my theory about the cooling. Another thing I noticed in the pics is the shaft going to the front diff. That looks like a pretty severe down and to the side angle.I can't wait to see it run.
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Old 01-20-2012, 05:24 AM
  #27
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Ok, we have different opinions about cooling. That's fine.

If you look closely it is not the shaft going to front diff that has a big angle but the one going to the rear diff. And yes it does have a lot of angle but still within drive cup limits. It is also silicone bushed inside. And it does not have practically any down or up angle, only to the right.

"Hell of a load to the engine"... okay I think I disagree here also. That engine is intended for an aeroplane in a 12-15 kilos weight range and it is supposed to power 3D aerobatic planes with ease with lots of G's and strong acceleration from hover. This taken into account I think it does not need to work extensively hard in my application. Tire traction will always be the most limiting factor of putting the power to the ground. I think the most obvious parts to break are various parts of the drivetrain.

Your first comment was very "attacking" by nature. Instead of saying "that is not possible" you could consider taking an easier approach. For instance asking questions. That would help other people too. With that kinda responses you only get people angry or irritated.
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Old 01-20-2012, 11:05 AM
  #28
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Grille made out of aluminum, this is what it looks like on the body:


Here's the original 1:1 Mk1 Ford Escort grille:


And here's the grille I made painted to match the original style:


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Old 01-20-2012, 11:45 AM
  #29
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

You can look at the Losi also and that has a pretty good angle on the driveshaft,and there is no problemswith that,ifanything you will probally have issues withdogbones or drive cups likeyou disscused.
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Old 01-20-2012, 02:59 PM
  #30
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Ahh, very nice grille! I love such details
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Old 01-20-2012, 05:43 PM
  #31
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale


Quote:
ORIGINAL: JariV

Ok, we have different opinions about cooling. That's fine.

If you look closely it is not the shaft going to front diff that has a big angle but the one going to the rear diff. And yes it does have a lot of angle but still within drive cup limits. It is also silicone bushed inside. And it does not have practically any down or up angle, only to the right.

"Hell of a load to the engine"... okay I think I disagree here also. That engine is intended for an aeroplane in a 12-15 kilos weight range and it is supposed to power 3D aerobatic planes with ease with lots of G's and strong acceleration from hover. This taken into account I think it does not need to work extensively hard in my application. Tire traction will always be the most limiting factor of putting the power to the ground. I think the most obvious parts to break are various parts of the drivetrain.

Your first comment was very "attacking" by nature. Instead of saying "that is not possible" you could consider taking an easier approach. For instance asking questions. That would help other people too. With that kinda responses you only get people angry or irritated.
The bottom line is I would hate to see it not work right considering all the time and money your investing there.
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Old 01-20-2012, 06:52 PM
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

awesome build and the pipes are works of art... i cant wait to see and hear video of it running. again, great work.
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Old 01-20-2012, 08:35 PM
  #33
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Thank you again to all.
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Old 01-21-2012, 05:40 AM
  #34
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

i love mk1 escorts with the rally arches, will look very good when painted up have you got a colour scheme for it?



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Old 01-21-2012, 06:01 AM
  #35
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

nice job, also nice to see someone who races karts and is addicted to rc as well!
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Old 01-26-2012, 05:51 AM
  #36
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Have you started her up yet?

I would think IF you do have heat issues, you could use some ducting, if this does't help look into brushless turbine fans - i used one on my 57cc twin and it works a treat.

Craig
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Old 01-26-2012, 08:32 AM
  #37
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

I prepped everything today to be ready for the first start. I am still waiting for the sensors to arrive for the engine monitoring unit.

That unit measures cylinder head temperature for both heads and exhaust gas temperature for both cylinders and revolutions of the engine. It does all the functions simultaneously and has warning limits that set off a red color LED on. And a LCD display. So I will install that to the car and then I will be ready to fire up.

I measured the weight distribution of the car today.

53% of total weight on rear axle and 47% in the front axle.

Left side 49,5%, right side 50,5%.

I would have wanted 50-52% of the weight on the front axle so the manoveurability under full or partial load would have been neutral and no understeer (typical to 4WDs). I should have placed the engine a little bit forward than what it is but it was impossible to know exactly beforehand. I thought that position would have been enough.

BTW; all of you who have weight scales and a 4WD rc car please could you measure your cars corner weights? I would like to have comparison data. Post weights in driving condition with full tank of gas, either normal house scale or a fish scale. Measure the weight on all wheels. I would like to know what kind of weight distribution known brands have.
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Old 01-30-2012, 01:59 AM
  #38
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Wow Jari,
You're at it again![8D]

Nice work man.

Maybe orange & white like the Mk 1 buggy?
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Old 01-30-2012, 02:59 AM
  #39
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

subbed 8)
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Old 01-30-2012, 10:29 PM
  #40
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Mudgy, I was considering that but decided that I don't want to repeat myself. So I decided on another color combo. The shell is being painted now and I should have it back later on this week. Let's see how it turns out.

Blaaaaah, still no word on the sensors. I'm expecting for them to arrive late this week too.
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Old 02-01-2012, 04:45 AM
  #41
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

This looks like a fantastic build and it would be great to see a full grid of these at the first Finland RC federation meeting for largescale rally cars - I bet you could set it up in no time at all.

There are obviously many hours of R&D left to do but it's looking great so far.

Mike
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Old 02-03-2012, 02:10 PM
  #42
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

We actually have a lot of 1/4 scale rallycars here. We also have winter racing series and summer as well.

Here's some picture terror:



















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Old 02-03-2012, 03:36 PM
  #43
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Damn, that looks killer!
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Old 02-03-2012, 04:14 PM
  #44
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

That's wicked!!! Nice job so far!!!
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Old 02-03-2012, 04:57 PM
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

awesome, ready to run ? looking forward to seeing and hearing it [8D]
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Old 02-03-2012, 04:58 PM
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

That is just so cool looking!
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Old 02-03-2012, 08:56 PM
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Nice colour scheme.

Very nice.







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Old 02-03-2012, 09:46 PM
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Thank you.

I'm ready to try to fire it up but the sensors didn't come in the mail yet. I'm not taking any chances with the engine so until I have the monitoring unit on I will not even try to start the engine.
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Old 02-10-2012, 05:18 PM
  #49
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale


Quote:
ORIGINAL: JariV

Thank you.

I'm ready to try to fire it up but the sensors didn't come in the mail yet. I'm not taking any chances with the engine so until I have the monitoring unit on I will not even try to start the engine.
Sensors? Monitoring unit? What are you monitoring that your afraid to fire it up?
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Old 02-17-2012, 10:09 PM
  #50
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Default RE: BAJA SRT4 100cc gasoline twin cylinder 2-stroke 1/4 scale

Ahh Johnny,

how many vehicles have YOU manufactured?

I would keep very quiet if I was you, until it's running. The egg on your face won't show that way[sm=47_47.gif].
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